Christopher Calvin Garnier, charged with second-degree murder in the death of Truro police officer Const. Catherine Campbell, is seen entering the courtroom. THE CANADIAN PRESS

UPDATE 1 p.m. Dec. 14:

Dr. Stephen John Hucker was back on the stand today at the murder trial for Christopher Garnier in Halifax discussing the legal defence of automatism, a state of impaired consciousness with no voluntary action. It can result from disorders such as schizophrenia, brain injury, or from going through a traumatic event. Garnier had automatism, said Hucker.

Hucker also said that people who suffer emotional trauma cannot remember parts of the event that happened. He noted that Garnier's lack of sleep before his police interview "could aggravate it," saying that he had Acute Stress Disorder. He said that people with this condition cannot gather thoughts, feel confused and dismayed.

"They basically feel stunned," said Hucker.

Hucker said that police interviewing Garnier used a suggestive style of questioning, for example by saying there was blood everywhere and a struggle when Catherine Campbell died.

"It's certainly possible that someone suffering from acute stress disorder can be more suggestible," Hucker said.

Prosecutor Carla Ball cross-examined Hucker. She said that Garnier's alleged actions in the early hours of Sept. 11, 2015 were in fact logical: hiding Campbell's body in a bin, removing bloodied clothing and throwing the necklace on a roof. Dragging the bin through the streets at 5 a.m. when they are not lit up was also logical, as was dumping the body in brush with a box on top, said Ball. She said that evidence was hidden in six different places.

The cross-examination discussed auto-erotic (self-choking) and erotic asphyxiation (done with a partner). If a person dies, there is no suicide notes at the scene. Pornography relating to choking and other sex aids are often found with the body. The body is often naked.

Two security video clips were shown of a man wheeling a bin in the small hours of Sept. 11, 2015.

Next defence witness is Truro Police officer Justin Russell. He graduated with Campbell and both trained and worked with her. Training included how to break and release oneself from chokeholds and self-defence.

••••

A forensic psychiatrist who examined Christopher Garnier said he had post-traumatic stress disorder after the death of Catherine Campbell, he said at his trial in Halifax Wednesday.

Dr. Stephen John Hucker said that Garnier suffered acute stress disorder on the night that Campbell died, unable to think clearly and suffering symptoms of 'dissociation', feeling detached from his body in a state described as trance-like.

When Hucker examined Garnier last year, he noticed PTSD symptoms including hypervigilance and an unwillingness to relive the event or see people connected to it, such as his friend who lived in the apartment where Campbell died.

"He had most of the symptoms," said Hucker.

Garnier is accused of strangling Campbell in a McCully Street apartment and dumping her body underneath Halifax's Macdonald Bridge using a green bin in the early morning of Sept. 11, 2015.

But Hucker said that Garnier's behaviour at the time of his alleged offence showed a person unable to think clearly.

At the time Campbell died, Hucker said Garnier "just sort of stood there looking."

"He was at a loss to explain why he had not called 911 or administered life-saving treatment to Ms. Campbell," said Hucker.

He said that Garnier then put Campbell's body in the bin and wheeled it barefoot through lit city streets and was seen by witnesses, one of whom saw him screaming and cursing.

Hucker told the court that Garnier did not put Campbell's body in his car and dump it in a more secluded location.

"Had he been thinking logically and rationally he would have done that," said Hucker.

When he saw Garnier in 2016, he noted that his memory of Sept. 11, 2015 was generally patchy.

However, Hucker said that Garnier was co-operative and answered questions to the best of his ability.

"He showed no signs of agitation," said Hucker.

Garnier reported having tunnel vision and a noise like rush hour traffic ringing in his head. These were symptoms of acute stress disorder, said Hucker. "People who are in that state are often frightened, panicky, confused," he said. Garnier also had little memory of Sept. 11 to Sept. 13, 2015. The condition can also cloud judgment and decision making, which does not follow a logical pattern.

On Monday Garnier told the court that Campbell, who came back to McCully with him from the Halifax Alehouse, asked to be hit and choked.

Hucker said that he had previously seen clients who engaged in potentially dangerous activities such as erotic choking.

In the event of strangulation, consciousness can be lost in seconds.

"Some forms of sexual masochism are either very harmful or life-threatening," said Hucker.

However, in a non-consensual strangulation, a victim would express shock before desperately fighting back.

Hucker said he would have expected Garnier to have had some injuries resulting from a struggle.